Method of manufacturing sheet metal



UNITED STATES PATENT QFFIGE.

ISAAC E. CRAIG, OF TROY, OHIO.-

METHOD OF MANUFACTURING SHEET METAL.

SPECIFICATION forming part of Letters Patent No. 501,705, dated July 18,1893.

Application filed January 31, 1893- Serial No. 460,462. (No specimens.)

To all whom it may concern:

Be it known that I, IsAAO E. CRAIG, a citizen of the United States,residing at Troy, in the county of Miami and State of Ohio, haveinvented a certain new and useful Improvement in the Manufacture ofSheet-Iron, of which the following is a specification.

My invention relates to the production of sheet iron having a pleasingand uniform dark color over its surface without resort to the slow andexpensive method of rolling known as the loose process. This object Iattain by the application of a strong jet of steam or water to the edgesof piles or packagesof sheets in the manner hereinafter set forth; and Ido hereby declare the following to be a full clear and exact descriptionof the invention, which will enable others skilled in the art to whichit relates to make and use the same. i

In the ordinary or tight method of reducing iron to sheets, the entirepack consisting usually of from four to six sheets are allowed to stickfirmly together and by successive passes between the rolls while hotreduced to the desired gage. In this method the air is in a greatmeasure excluded from the interior surfaces of the sheets, and whenfinished they show very imperfect and irregular oxidation and thevariety of colors corresponding thereto, and this is but slightlyimproved by the subsequent annealing either in the tight box or openfurnace.

To carry my invention into effect I roll and anneal in the tight box inthe ordinary wayexcepting only-that instead of allowing the charge ofthe box to 0001 before the box is opened, I wait only until such time asthe box has become black and then by the ordinary means lift theinverted box from its bedplate on which the charge is piled up, when thecharge will be found to be still at a moderate red heat. At this time aworkman approaches one side of the pile of red hot sheets so uncovered,bearing the nozzle of a steam hose which said nozzle should consist of apiece of one half inch gas pipe connected by strong three quarter inchvulcanized rubber hose, with any source of steam supply of not.

less than sixty to one hundred pounds pressure per square inch, anddirect from the nozzle piece of gas pipe, which should be of sufficientlength namely six or seven feet a cur rent of steam against the edge ofthe top of the pile moving the nozzle from end to end thereof. With thesteam pressure above stated the current is sufficiently energetic toslightly lift and open up so as to allow admission to the current,thirty to fifty sheets on top of the pile. When the nozzle has thus beenpassed two or three times from end to end, with its point in contact ornearly so with the edges of the sheets-the pile should be begun to betaken down by workmen grasping fifteen or twenty sheets at a time withtongsin the usual manner and removing them to the place where it isdesired to again pile them up, and the jet of steam be continued on theedge of the top of the pile until it is all in this manner removed. Ifind it best in practice and prefer that the end of the nozzle pieceshould be so flattened as to reduce its opening to a slit about onethirty second of an inch across and in using it hold it in such a mannerthat the greater dimension or length of this slit be kept up and down.Sheet iron so treated is found to have acquired from decomposition ofsteam and attendant oxidation of the sheets a close and continuouscoating of magnetic oxide, showing, however, some difierence of colorbetween the oxide formed by the steaming operation and the patches ofoxide formed while being rolled. This however is entirely avoided whenthe charge of the annealing box has been pickled or otherwise cleaned ofits oxide before being stacked up 'for annealing in which case ahandsome and uniform color is given to the entire sheet. The same effectis produced in substantially the same manner when instead of steam thenozzle discharges water, preferably hot, in the form of spray, which onentering between the sheets is immediately converted into steam, andwhile under some conditions and circumstances this latter method may bepreferred it will ordinarily be found best to use the steam jet.

I am aware that the well known power of red hot iron to decompose steamand appropriate the oxygen has been utilized invarious industrialoperations and thatit has been to some extent practiced to oxidize sheetiron by handling one sheet at a time and directing atright angles ornearly so against its surface a considerable number of jets of steamamethod which on account of it leaving the sheets greatly warped andbuckled is not available for ordinary use-but believe that steamoxidation of sheets by introducing the steam or water between the edgesof the sheets while in packs or piles has not heretofore been used.

It sometimes happens that from inattent'ion the charge of an annealingbox is allowed to become so hot that the lower part of the contentshaving great weight above resting on it is caused to slightly adheresheet to sheet. In annealing to afterward color as here described thisoverheating must be avoided.

to enter between the sheets contained in such 2 5 acka e or ile. p 7 D pISAAC E. CRAIG.

Witnesses:

ALEX. R, HAWTHORNE, 0. P. SAUNDERS.

